Our overall objective is to study the mechanisms involved in the uptake of choline and the synthesis and release of acetylcholine (ACh) using cortical synaptosomal preparations that are preincubated with (methyl-3H) choline in order to effect the synthesis of labeled Ach. We are continuing to investigate the effects of a variety of agents such as black widow spider venom, somatostatin, and sulfhydryl reagents on the release of the neurotransmitter. We are initiating studies to determine if Na-K-ATPase may be involved in release.